(a) Field of the Invention
The present invention relates to a system and a method for controlling regenerative braking of an electric vehicle. More particularly, the present invention relates to a system and a method for controlling regenerative braking of an electric vehicle by calculating an available torque considering a battery system and an available torque considering a motor system and improving an accuracy of regenerative braking amount by calculating a regenerative braking capacity based on a minimum torque between the available torque considering the battery system and the available torque considering the motor system.
(b) Description of the Related Art
Electric vehicles are classified into as a pure electric vehicle in which a motor is driven using electrical energy charged in a battery, a fuel cell vehicle in which the motor is driven using a fuel cell, and a hybrid electric vehicle using combined system of the motor and an engine. The electric vehicles use regenerative braking technology when a braking control based on a brake pedal is performed. In other words, the regenerative braking of the electric vehicle is a technology which applies a counter torque to the motor using energy generated during braking to generate electric energy and stores the generated electric energy in a battery.
For the regenerative braking, a brake controller is configured to calculate a total braking amount when a driver requests a brake, and a vehicle controller is configured to calculate a regenerative braking amount by considering an operating state of the motor. In addition, the brake controller is configured to calculate a total braking amount, and the vehicle controller is configured to calculate a regenerative braking capacity based on the regenerative braking amount. After that, the brake controller is configured to adjust hydraulic pressure supplied to a brake cylinder of a wheel to satisfy the total braking amount.
In other words, the brake controller is configured to divide the total braking amount into the regenerative braking capacity and the hydraulic pressure braking amount, and adjust hydraulic pressure by receiving the regenerative braking amount from the vehicle controller. Therefore, the brake of the electric vehicle may be performed by a cooperative control of the brake controller and the vehicle controller. However, according to a conventional art the brake controller calculates the regenerative braking capacity based on a wheel torque calculated by a maximum motor torque. Accordingly, when a battery system or a motor system is restricted, the brake controller may calculate the regenerative braking capacity correctly. Moreover, an initial brake based on communication delay while receiving the regenerative braking amount from the vehicle controller may cause further issues in controlling the vehicle.
The above information disclosed in this section is merely for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.